<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>HelloController</title>
</head>
<body>
<h1>thymeleaf模板引擎渲染的</h1>
后端参数msg 为<h1 th:text="${msg}"> 默认值，会被替换</h1>
</body>
</html>
